With the increase of the processing speed and the integration density of a semiconductor chip, in a server equipped with semiconductor chips, the semiconductor chips are connected to each other by micro wiring, and the transmission speed of a signal is increased between the semiconductor chips. Further, a three-dimensional mounting has been developed which implements the high speed transmission of a signal by forming through vias (through silicon vias (hereinafter, referred to as “TSVs”)) in semiconductor chips and laminating and connecting the semiconductor chips to each other by micro bumps. However, when TSVs is formed in a semiconductor chip, the semiconductor chip itself becomes expensive. Thus, the use of the three-dimensional mounting is limited to, for example, a memory.
In addition, a 2.5-dimensional mounting has been developed in which a silicon interposer is disposed as an intermediate board between a semiconductor chip and a printed circuit board so as to transmit a signal at a high speed through the silicon interposer. While the 2.5-dimensional mounting is also excellent in the high speed transmission of a signal, this mounting also requires the formation of TSVs in the silicon interposer thereby causing the high cost. Hence, using a resin interposer employing a resin for the purpose of reducing the cost has been reviewed.
However, since the resin interposer is entirely formed of a resin layer even including a wiring layer, the warpage of the resin interposer may increase. Hence, when the resin interposer having the large warpage is mounted on a printed circuit board, there is a problem in that the resin interposer and some bumps of the printed circuit board are not bonded to each other due to the influence of the warpage.
The followings are reference documents.    [Document 1] Japanese Laid-Open Patent Publication No. 2004-134817 and    [Document 2] Japanese Laid-Open Patent Publication No. 2006-156432.